A disk drive system typically has one or more magnetic recording disks and control mechanisms for storing data within approximately circular tracks on a disk. The magnetic recording disk is composed of a substrate and one or more layers deposited on the substrate. A disk substrate may be produced from a blank sheet of, for example, metal-based material such as aluminum or aluminum magnesium. The sheet may be punched to generate a disk substrate having an inner diameter (ID) and an outer diameter (OD). After removing the ID and OD, the disk-shaped substrate may be further processed (e.g., polished, textured, layer deposition, etc.) to produce the magnetic recording disk.
The trend in designing magnetic hard disk drives involves increasing the recording density of a disk drive system. Recording density is a measure of the amount of data that may be stored in a given area of disk. One method for increasing recording densities is to pattern the surface of the disk to form discrete tracks, referred to as discrete track recording (DTR). DTR disks typically have a series of concentric raised zones (a.k.a., lands, elevations, etc.) storing data and recessed zones (a.k.a., troughs, valleys, grooves, etc.) that may store servo information. The recessed zones separate the raised zones to inhibit or prevent the unintended storage of data in the raised zones.
One method of producing DTR magnetic recoding disks includes using a press to imprint embossable films residing on one or both sides of a disk substrate. The press utilizes a die for each side of the disk to be imprinted. The die includes a stamper that is pressed into the embossable film to form the imprinted pattern in the film. The pattern is subsequently transferred to the substrate and/or one or more layers residing above the substrate. Thin film magnetic recording layers are then sputtered over the patterned surface of the substrate to produce the DTR media having a continuous magnetic layer extending over both the raised zones and the recessed zones.
One prior imprinting apparatus described in WO 03/090985, and illustrated in FIG. 1A herein, utilizes stampers 6 and 8 that are sealed to chambers 28 and 30, respectively, utilizing gaskets 32 and 34, respectively. Pressurize air is supplied to the chambers 28 and 30 to generate forces in each chamber that will act simultaneously to press on the stampers 6 and 8. The stampers 6 and 8 are each further provided with a corresponding fluid channel 46 and 48, respectively, to receive pressurized air and holes to eject the air in order to facilitate removal of the stampers 6 and 8 from the substrate 26 after imprinting. One problem with the apparatus described in WO 03/090985 is the chambers 28 and 30 extend over the outer edge of the substrate 26 (with their corresponding gaskets being positioned far from edges of the substrate) without a support structure underneath. The lack of a supporting structure near the outer edge of the substrate 26 between stampers 6 and 8 may result in inconsistent imprinting near the outer portions of substrate 26 relative to other portions of the substrate.
Another prior imprinting apparatus described in U.S. Pat. No. 6,482,742, illustrated in FIG. 1B herein, utilizes a pressure cap 72 having an internal chamber 73 for receiving pressurized fluid. The pressurized fluid within the chamber 73 produces fluid jets through cap openings 71 that press a stamper 10 against an embossable film 21. The cap 72 includes a groove 77, holding an o-ring 78, along a perimeter of the face adjacent to the stamper 10. One problem with the apparatus described in U.S. Pat. No. 6,482,742 is that there is no support structure under the outer edges of stamper 10, which may result in inconsistent imprinting near the outer portions of embossable film 21 relative to other portions of the film.
Another limitation of each of the imprinting apparatus described in WO 03/090985 and U.S. Pat. No. 6,482,742 is that they are designed for use with hole-less substrates such as silicon wafers used in the semiconductor industry. In particular, WO 03/090985 and U.S. Pat. No. 6,482,742 describe sealing arrangements utilizing only outer o-rings or gaskets. Such press apparatus may not be suitable for use with substrates such as magnetic recording disks that have holes. In particular, conventional presses for magnetic recording disks utilize a mandrel, or shaft, having a diameter that is sized to engage the ID of the disk. The dies have a cylindrical opening sized to receive the mandrel. The stampers are disposed around the mandrel and, thus, have an annular shape with an inner diameter (i.e., a hole, or cavity, at their centers). Accordingly, an inner diameter sealing arrangement is required for such press apparatus that is not addressed by WO 03/090985 and U.S. Pat. No. 6,482,742.